Proposed Research

Coastal Zone development has dramatically increased the transfer of
nutrients from the continental margin to the sea. In the past, concern
has focused on nitrates, ammonia, and phosphates; inorganic forms
of nutrients. However, as watersheds are developed, the amount of
organic nitrogen loading increases proportionally. Dissolved organic
nitrogen (DON) can contribute up to 80% of the total nutrient loading
in developed watersheds. DON has been considered to be largely inert,
cycling on long time scales and not contributing to coastal zone eutrophication.
However, there is now good evidence that DON is utilized directly
as a nutrient by some marine algae, including species which contribute
to harmful algal blooms. Utilization of DON as a nutrient fundamentally
changes our concepts of nutrient cycling in seawater. We do not know
what DON is, or how it is used by marine algae as a nutrient. Using
facilities uniquely available at WHOI, we have evidence that DON may
made of specific proteins that are somehow resistant to microbiological
degradation. We propose to investigate the chemical and molecular
biological characteristics of DON in order to better understand its
fundamental chemical properties and develop appropriate tools needed
to more fully investigate its origin and fate in the marine environment.

Daniel Repeta

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